The present invention is related to dual air actuator for operating an air chuck. More particularly, the present invention is directed to a dual air actuator for operating an air chuck on a balancing machine to couple a drive shaft thereto.
The use of air pressure to actuate air chucks for coupling devices to machines, such as shaft balancing machines, is widely practiced. Exemplary of an air chuck is U.S. Pat. No. 5,106,244, incorporated herein in its entirety. In the past devices such as drive shaft balancing machines employed rotating air lines to carry a constant source of operating air to air actuate jaw members. These rotating air lines proved difficult to balance and transmitted vibration to the balancing machine Since the rotating air lines were subject to friction wear, arrangements were developed utilizing stationary air lines with springs to return actuators for air chucks to a decoupled mode. It has been found that these spring couplings stick or lock resulting in weak and/or broken springs. Therefore, there is a need for an air coupling used with balancing machines which does not have the drawback of broken springs requiring substantial machine down time, inconvenience and aggravation to repair, only to have the same failure reoccur.
The present invention is directed to an air actuator for actuating and providing air to an air chuck which couples an object for rotation wherein the actuator comprise a housing defining cylindrical chamber having a first stop surface and a second stop surface. A first pressure line is connected to a first side of the chamber and a second pressure line is connected to a second side of the chamber for applying pressure to the first and second sides of the chamber, respectively. An operating shaft is positioned within the chamber for movement between a first position adjacent to the first stop surface and a second position adjacent to the second stop surface, the shaft having a longitudinal bore for delivering air to the pneumatic chuck, which longitudinal bore is in communication with a radially extending bore. A piston is disposed around the operating shaft and is reciprocally mounted in the chamber for movement between the first stop surface and the second stop surface, wherein when pressurized air is applied to the first side of the chamber, the piston is shifted from the first stop surface against the second stop surface at the second side of the chamber. This allows pressurized air to flow through the bores in the operating shaft to the air chuck. When pressurized air is applied to the second side of the chamber, the piston moves away from the second stop surface from the second position back to the first position. This disengages the operating shaft from the clutch and decouples the chuck and the object being rotated.
In a specific aspect of the invention, the operating shaft is not biased by a spring.
In still another aspect of the invention, the radially extending bore in the operating shaft is closed when the operating shaft is in the first position and open when the operating shaft is in the second position.